User interface for a portion of a display screen



The single FIGURE is a front view of a user interface for a portion of a display screen showing my new design.

The jagged outer broken line is included for the purpose of showing a portion of a display screen and forms no part of the claimed design. The portions of the user interface for a portion of a display screen shown in broken line form no part of the claimed design. 

The ornamental design for a user interface for a portion of a display screen, as shown and described. 